Jet McCabe is a character in the 1987 TV series episode "The Showdown". At some point prior to the events of the episode, he and Carter were both students at the same martial arts academy, but he was expelled for cheating. He seemingly blamed Carter for this event. He tracked Carter down and challenged him to a martial arts battle, which was interrupted by Michelangelo.
While Carter and the Turtles were intervening on a scheme of Dregg's, Jet broke into Carter's lab and stole the Turboflex, a mechanical suit that Carter had invented that gave the user immense strength. However, before he could do anything with it, he, Carter, Michelangelo and Leonardo were all transported to an alien gladiatorial arena where they were forced to fight alien creatures.
Despite his situation, Jet remained obsessed with fighting Carter, and even jeopardized their escape by trying to fight him. Carter immobilized the Turboflex by tricking Jet into performing a martial-arts move that would cause it to freeze. However, Jet refused to leave the gladiatorial arena with the Turtles and Carter, saying that this was one place he wouldn't be thrown out of.